1. Field of the Invention
The present invention relates to a wide gap semiconductor device, and a method for manufacturing a wide gap semiconductor device. More particularly, the present invention relates to a wide gap semiconductor device that can alleviate the electric field at the interface between a Schottky electrode and a substrate, and a method for manufacturing such a wide gap semiconductor device.
2. Description of the Background Art
Semiconductor devices such as a Schottky barrier diode (SBD) and junction barrier Schottky diode (JBS) have a configuration in which a Schottky electrode is formed on a substrate. Since the work function difference between metal qualified as the electrode material and semiconductor is small in a Schottky barrier diode, the leakage current during application of reverse voltage readily becomes great as compared to that of a PN diode. Therefore, various configurations are proposed in order to reduce leakage current.
For example, Japanese Patent Laying-Open No. 2001-85704 discloses a silicon carbide Schottky diode including a p+ guard ring region formed at the region of the substrate adjoining a perimeter region of the Schottky electrode, having a pn junction developed in contact with the main surface of the substrate. Further, Japanese Patent Laying-Open No. 2009-16603 discloses a junction barrier Schottky diode having a plurality of p type layers formed concentrically at a substrate adjoining a Schottky electrode.